Math Problem Statement

Find an equation for the line in the graph.

Solution

To find the equation of the line in the image, we can use the slope-intercept form of a line equation, y=mx+by = mx + b, where:

  • mm is the slope of the line
  • bb is the y-intercept (the point where the line crosses the y-axis)

Step 1: Determine the slope mm

We can calculate the slope by selecting two points on the line. From the graph:

  • Point 1: (4,0)(-4, 0)
  • Point 2: (0,4)(0, -4)

The formula for slope mm is: m=y2y1x2x1m = \frac{y_2 - y_1}{x_2 - x_1}

Substituting the coordinates of the two points: m=400(4)=44=1m = \frac{-4 - 0}{0 - (-4)} = \frac{-4}{4} = -1

Step 2: Find the y-intercept bb

From the graph, the line crosses the y-axis at (0,4)(0, -4), so the y-intercept b=4b = -4.

Step 3: Write the equation

Using the slope-intercept form y=mx+by = mx + b and substituting m=1m = -1 and b=4b = -4: y=x4y = -x - 4

Thus, the equation of the line is: y=x4y = -x - 4

Would you like more details on how this equation was derived or any other questions?

Here are some follow-up questions:

  1. What is the significance of the slope in a line's equation?
  2. How would the equation change if the slope was positive?
  3. Can the slope be zero, and what would that represent graphically?
  4. How can we find the x-intercept of a line from its equation?
  5. What happens to the graph of a line if we change only the y-intercept?

Tip: Always ensure you accurately choose two points on the graph when calculating the slope for the best results.

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Math Problem Analysis

Mathematical Concepts

Algebra
Linear Equations
Slope-Intercept Form

Formulas

Slope formula: m = (y2 - y1) / (x2 - x1)
Slope-intercept form: y = mx + b

Theorems

Equation of a Line

Suitable Grade Level

Grades 8-10